The present invention relates to septa used in catheter and introducer needle assemblies. In medicine, such catheter and introducer needle assemblies are used to place a catheter properly into the vascular system of a patient. Once in place, catheters, such as intravenous (or “IV”) catheters, may be used to infuse fluids including normal saline, medicinal compounds, and/or nutritional compositions (including total parenteral nutrition, or “TPN”) into a patient in need of such treatment. Catheters additionally enable the removal of fluids from the circulatory system and the monitoring of conditions within the vascular system of the patient.
One type of commonly used catheter is an “over-the-needle” catheter that is mounted over an introducer needle with a sharp distal tip. The introducer needle cuts through the patient's skin and provides structural support to the catheter as it advances through the skin. The distal edge of the catheter grips the outside of the introducer needle to facilitate the insertion of the catheter through the skin along with the introducer needle. When a portion of the introducer needle is inserted into the target vessel, the catheter is slid over the introducer needle into place within the target vessel. Once placement of the catheter has been confirmed, the introducer needle may be withdrawn from the catheter assembly, leaving the catheter in place.
As blood begins to flow into the catheter adapter, a variety of seals or septa can be in place within the catheter adapter for preventing outflow of fluid from the catheter assembly. Such a septum may rely on an interference fit between the catheter assembly and the introducer needle assembly to create radial compression forces on the introducer needle intended to prevent the unwanted escape of blood between the septum and the introducer needle. The compression forces operating on the introducer needle can also function to close the septum and maintain the septum closed after the introducer needle is removed. The interference fit closing the septum after needle withdrawal can introduce frictional forces at the needle-septum interface. These frictional forces can create drag forces that resist needle extraction, making it difficult for medical personnel to remove the needle from the catheter assembly, particularly with one hand. Occasionally, the frictional force required to remove the needle can result in uncomfortable or painful movement or vibration of the catheter within the patient. It would thus be an improvement in the art to provide a septum that has a lower frictional force resisting needle extraction while still providing adequate sealing functionality.